The present invention relates to novel phosphosulphur compounds (i.e. sulphur and phosphor-containing) and their use as petroleum additives, particularly as antioxidant, antiwear, extreme-pressure and anticorrosive additives for lubricating oils.
Antiwear and extreme-pressure additives have been used for decades particularly in engine oils, transmission fluids and hydraulic fluids. Numerous additive types have been developed and several of them have made it possible to very significantly reduce deterioration to mechanisms and therefore extend their life.
Among the antiwear and extreme-pressure additives the most active and therefore the most significantly industrially developed have been dialkyl and diaryl dithiophosphates and metallic dialkyl dithiocarbamates, (particularly those of zinc), alkyl thiophosphates, tricresyl phosphate, didodecyl phosphate, sulphurized terpenes, sulphur-containing spermaceti oil and various chlorine compounds. Certain of them are described in U.S. Pat. Nos. 2,364,283, 2,364,284, 2,365,938, 2,410,650, 2,438,876, 3,190,833. These are generally compounds containing heteroatoms such as sulphur and phosphorus, either alone (e.g. tricresyl phosphate, sulphur-containing terpenes and dithiocarbamates) or in combination (e.g. metallic dialkyl dithiophosphates and alkyl thiophosphates). Reference can be made to French Patents FR-A-982 719 and 1 321 821 and U.S. Pat. Nos. 2,750,342 and 3,944,495.
The phosphosulphur compounds used previously have relative sulphur and phosphorus quantites which are imposed by the stoichiometry of the reactions during their synthesis and which in particular give them antiwear and extreme-pressure properties, which cannot be modified by the Expert.